Cold weather has an upside, if you’re a grey wolf or whitefish

Frigid Torontonians cheered the return of slightly less terrible weather Thursday. But January’s dispiriting cold had an ecological upside, and some people — lovers of a beleaguered wolf population, haters of an invasive pest and anyone who likes whitefish — were deeply appreciative of the deep freeze and perhaps even hopeful for more.

For just the third time in 15 years, an ice bridge has formed linking Isle Royale in Lake Superior to the mainland near Thunder Bay.

Isle Royale is home to a threatened grey wolf population: eight wolves remained at last count and they are deeply inbred, so their pups have trouble surviving. The last addition to the island gene pool, a male nicknamed Old Grey Guy, arrived from the stable mainland population by ice bridge in 1997…